<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    .container{
      width: 400px;
      height: 400px;
      border: 1px solid #333;
      display: flex;
      align-items: flex-end;
      flex-direction: row-reverse;
    }
    .box{
      width: 100px;
      height: 100px;
      background: blue;
    }
    .box:nth-child(2){
      background: red;
    }
    .box:nth-child(3){
      background: yellow;
    }
  </style>
</head>
<body>
  <div class="container">
    <div class="box">1</div>
    <div class="box">2</div>
    <div class="box">3</div>
  </div>
</body>
</html>
